The problem of engine wear in diesel engines operating on hydrocarbon fuels has become increasingly serious with the recent shift to the use of both lighter and cleaner burning diesel fuel oils, and with the use of alcohols, such as methanol and ethanol, in the place of conventionally petroleum derived diesel fuels as disclosed in Brazilian Patent Application No. P17700392. Of particular concern are wear problems associated with the fuel injector mechanisms used in such engines. This problem is also of concern in fuel compositions comprising mixtures of alcohols and petroleum derived diesel fuels such as those disclosed in the present invention.
Fatty acid dimers and the amine salts thereof have been used in hydrocarbon fluid compositions for many years. Their principle function appears to have been as hydrocarbon fluid rust or corrosion inhibitors. Typical background patents showing such use are U.S. Pat. No. 3,696,048, U.S. Pat. No. 2,822,330, U.S. Pat. No. 2,631,979, U.S. Pat. No. 2,632,695, and U.S. Pat. No. 3,017,354. Recently issued U.S. Pat. No. 4,002,437 discloses that the addition to light diesel fuel oils of (1) dimeric and trimeric acids produced by the condensation of unsaturated aliphatic monocarboxylic acids having between about 16 and about 18 carbon atoms per molecule and hydroxyaliphatic monocarboxylic acids having between about 16 and about 18 carbon atoms per molecule in combination with (2) a normally liquid completely or partially neutral amine salt of an oxo-alkyl acid ester of orthophosphoric acid in which each esterifying oxo-alkyl group contains 13 to 16 carbon atoms and the amine is an aliphatic hydrocarbon monoamine of 16 to 24 carbon atoms in which each aliphatic hydrocarbon radical is attached to the nitrogen through a saturated carbon atom, (3) an aliphatic demulsifier consisting of fatty acids alkoxylated by a mixture of ethylene and propylene oxides and (4) a saturated hydrocarbon solvent provides anti-wear properties to the so-called light diesel fuel oils.